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case object None extends Option[Nothing] with Product with Serializable

This case object represents non-existent values.

Annotations
@SerialVersionUID()
Source
Option.scala
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  1. None
  2. Option
  3. Serializable
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  6. IterableOnce
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Type Members

  1. class WithFilter extends AnyRef

    We need a whole WithFilter class to honor the "doesn't create a new collection" contract even though it seems unlikely to matter much in a collection with max size 1.

    We need a whole WithFilter class to honor the "doesn't create a new collection" contract even though it seems unlikely to matter much in a collection with max size 1.

    Definition Classes
    Option

Value Members

  1. final def collect[B](pf: PartialFunction[Nothing, B]): Option[B]

    Returns a scala.Some containing the result of applying pf to this scala.Option's contained value, if this option is nonempty and pf is defined for that value.

    Returns a scala.Some containing the result of applying pf to this scala.Option's contained value, if this option is nonempty and pf is defined for that value. Returns None otherwise.

    pf

    the partial function.

    returns

    the result of applying pf to this scala.Option's value (if possible), or None.

    Definition Classes
    Option
    Annotations
    @inline()
    Example:
    1. // Returns Some(HTTP) because the partial function covers the case.
      Some("http") collect {case "http" => "HTTP"}
      
      // Returns None because the partial function doesn't cover the case.
      Some("ftp") collect {case "http" => "HTTP"}
      
      // Returns None because the option is empty. There is no value to pass to the partial function.
      None collect {case value => value}
  2. final def contains[A1 >: Nothing](elem: A1): Boolean

    Tests whether the option contains a given value as an element.

    Tests whether the option contains a given value as an element.

    This is equivalent to:

    option match {
      case Some(x) => x == elem
      case None    => false
    }
    elem

    the element to test.

    returns

    true if the option has an element that is equal (as determined by ==) to elem, false otherwise.

    Definition Classes
    Option
    Example:
    1. // Returns true because Some instance contains string "something" which equals "something".
      Some("something") contains "something"
      
      // Returns false because "something" != "anything".
      Some("something") contains "anything"
      
      // Returns false when method called on None.
      None contains "anything"
  3. final def exists(p: (Nothing) => Boolean): Boolean

    Returns true if this option is nonempty and the predicate p returns true when applied to this scala.Option's value.

    Returns true if this option is nonempty and the predicate p returns true when applied to this scala.Option's value. Otherwise, returns false.

    This is equivalent to:

    option match {
      case Some(x) => p(x)
      case None    => false
    }
    p

    the predicate to test

    Definition Classes
    Option
    Annotations
    @inline()
  4. final def filter(p: (Nothing) => Boolean): Option[Nothing]

    Returns this scala.Option if it is nonempty and applying the predicate p to this scala.Option's value returns true.

    Returns this scala.Option if it is nonempty and applying the predicate p to this scala.Option's value returns true. Otherwise, return None.

    This is equivalent to:

    option match {
      case Some(x) if p(x) => Some(x)
      case _               => None
    }
    p

    the predicate used for testing.

    Definition Classes
    Option
    Annotations
    @inline()
  5. final def filterNot(p: (Nothing) => Boolean): Option[Nothing]

    Returns this scala.Option if it is nonempty and applying the predicate p to this scala.Option's value returns false.

    Returns this scala.Option if it is nonempty and applying the predicate p to this scala.Option's value returns false. Otherwise, return None.

    This is equivalent to:

    option match {
      case Some(x) if !p(x) => Some(x)
      case _                => None
    }
    p

    the predicate used for testing.

    Definition Classes
    Option
    Annotations
    @inline()
  6. final def flatMap[B](f: (Nothing) => Option[B]): Option[B]

    Returns the result of applying f to this scala.Option's value if this scala.Option is nonempty.

    Returns the result of applying f to this scala.Option's value if this scala.Option is nonempty. Returns None if this scala.Option is empty. Slightly different from map in that f is expected to return an scala.Option (which could be None).

    This is equivalent to:

    option match {
      case Some(x) => f(x)
      case None    => None
    }
    f

    the function to apply

    Definition Classes
    Option
    Annotations
    @inline()
    See also

    map

    foreach

  7. def flatten[B](implicit ev: <:<[Nothing, Option[B]]): Option[B]

    Returns the nested scala.Option value if it is nonempty.

    Returns the nested scala.Option value if it is nonempty. Otherwise, return None.

    This is equivalent to:

    option match {
      case Some(Some(b)) => Some(b)
      case _             => None
    }
    ev

    an implicit conversion that asserts that the value is also an scala.Option.

    Definition Classes
    Option
    Example:
    1. Some(Some("something")).flatten
    See also

    flatMap

  8. final def fold[B](ifEmpty: => B)(f: (Nothing) => B): B

    Returns the result of applying f to this scala.Option's value if the scala.Option is nonempty.

    Returns the result of applying f to this scala.Option's value if the scala.Option is nonempty. Otherwise, evaluates expression ifEmpty.

    This is equivalent to:

    option match {
      case Some(x) => f(x)
      case None    => ifEmpty
    }

    This is also equivalent to:

    option map f getOrElse ifEmpty
    ifEmpty

    the expression to evaluate if empty.

    f

    the function to apply if nonempty.

    Definition Classes
    Option
    Annotations
    @inline()
  9. final def forall(p: (Nothing) => Boolean): Boolean

    Returns true if this option is empty or the predicate p returns true when applied to this scala.Option's value.

    Returns true if this option is empty or the predicate p returns true when applied to this scala.Option's value.

    This is equivalent to:

    option match {
      case Some(x) => p(x)
      case None    => true
    }
    p

    the predicate to test

    Definition Classes
    Option
    Annotations
    @inline()
  10. final def foreach[U](f: (Nothing) => U): Unit

    Apply the given procedure f to the option's value, if it is nonempty.

    Apply the given procedure f to the option's value, if it is nonempty. Otherwise, do nothing.

    This is equivalent to:

    option match {
      case Some(x) => f(x)
      case None    => ()
    }
    f

    the procedure to apply.

    Definition Classes
    Option
    Annotations
    @inline()
    See also

    map

    flatMap

  11. def get: Nothing

    Returns the option's value.

    Returns the option's value.

    This is equivalent to:

    option match {
      case Some(x) => x
      case None    => throw new Exception
    }
    Definition Classes
    NoneOption
    Exceptions thrown

    NoSuchElementException if the option is empty.

    Note

    The option must be nonempty.

  12. final def getOrElse[B >: Nothing](default: => B): B

    Returns the option's value if the option is nonempty, otherwise return the result of evaluating default.

    Returns the option's value if the option is nonempty, otherwise return the result of evaluating default.

    This is equivalent to:

    option match {
      case Some(x) => x
      case None    => default
    }
    default

    the default expression.

    Definition Classes
    Option
    Annotations
    @inline()
  13. final def isDefined: Boolean

    Returns true if the option is an instance of scala.Some, false otherwise.

    Returns true if the option is an instance of scala.Some, false otherwise.

    This is equivalent to:

    option match {
      case Some(_) => true
      case None    => false
    }
    Definition Classes
    Option
  14. final def isEmpty: Boolean

    Returns true if the option is None, false otherwise.

    Returns true if the option is None, false otherwise.

    This is equivalent to:

    option match {
      case Some(_) => false
      case None    => true
    }
    Definition Classes
    Option
  15. def iterator: Iterator[Nothing]

    Returns a singleton iterator returning the scala.Option's value if it is nonempty, or an empty iterator if the option is empty.

    Returns a singleton iterator returning the scala.Option's value if it is nonempty, or an empty iterator if the option is empty.

    Definition Classes
    OptionIterableOnce
  16. final def knownSize: Int

    returns

    The number of elements in this option, if it can be cheaply computed, -1 otherwise. Cheaply usually means: Not requiring a collection traversal.

    Definition Classes
    OptionIterableOnce
  17. final def map[B](f: (Nothing) => B): Option[B]

    Returns a scala.Some containing the result of applying f to this scala.Option's value if this scala.Option is nonempty.

    Returns a scala.Some containing the result of applying f to this scala.Option's value if this scala.Option is nonempty. Otherwise return None.

    This is equivalent to:

    option match {
      case Some(x) => Some(f(x))
      case None    => None
    }
    f

    the function to apply

    Definition Classes
    Option
    Annotations
    @inline()
    Note

    This is similar to flatMap except here, f does not need to wrap its result in an scala.Option.

    See also

    flatMap

    foreach

  18. final def nonEmpty: Boolean

    Returns false if the option is None, true otherwise.

    Returns false if the option is None, true otherwise.

    This is equivalent to:

    option match {
      case Some(_) => true
      case None    => false
    }
    Definition Classes
    Option
    Note

    Implemented here to avoid the implicit conversion to Iterable.

  19. final def orElse[B >: Nothing](alternative: => Option[B]): Option[B]

    Returns this scala.Option if it is nonempty, otherwise return the result of evaluating alternative.

    Returns this scala.Option if it is nonempty, otherwise return the result of evaluating alternative.

    This is equivalent to:

    option match {
      case Some(x) => Some(x)
      case None    => alternative
    }
    alternative

    the alternative expression.

    Definition Classes
    Option
    Annotations
    @inline()
  20. final def orNull[A1 >: Nothing](implicit ev: <:<[Null, A1]): A1

    Returns the option's value if it is nonempty, or null if it is empty.

    Returns the option's value if it is nonempty, or null if it is empty.

    Although the use of null is discouraged, code written to use scala.Option must often interface with code that expects and returns nulls.

    This is equivalent to:

    option match {
      case Some(x) => x
      case None    => null
    }
    Definition Classes
    Option
    Annotations
    @inline()
    Example:
    1. val initialText: Option[String] = getInitialText
      val textField = new JComponent(initialText.orNull,20)
  21. def productElementName(n: Int): String

    The name of the nth element of this product, 0-based.

    The name of the nth element of this product, 0-based. In the default implementation, an empty string.

    n

    the index of the element name to return

    returns

    the name of the specified element

    Definition Classes
    Product
    Exceptions thrown

    IndexOutOfBoundsException if the n is out of range(n < 0 || n >= productArity).

  22. def productElementNames: Iterator[String]

    An iterator over the names of all the elements of this product.

    An iterator over the names of all the elements of this product.

    Definition Classes
    Product
  23. def stepper[S <: Stepper[_]](implicit shape: StepperShape[Nothing, S]): S

    Returns a scala.collection.Stepper for the elements of this collection.

    Returns a scala.collection.Stepper for the elements of this collection.

    The Stepper enables creating a Java stream to operate on the collection, see scala.jdk.StreamConverters. For collections holding primitive values, the Stepper can be used as an iterator which doesn't box the elements.

    The implicit scala.collection.StepperShape parameter defines the resulting Stepper type according to the element type of this collection.

    Note that this method is overridden in subclasses and the return type is refined to S with EfficientSplit, for example scala.collection.IndexedSeqOps.stepper. For Steppers marked with scala.collection.Stepper.EfficientSplit, the converters in scala.jdk.StreamConverters allow creating parallel streams, whereas bare Steppers can be converted only to sequential streams.

    Definition Classes
    IterableOnce
  24. final def toLeft[X](right: => X): Either[Nothing, X]

    Returns a scala.util.Right containing the given argument right if this is empty, or a scala.util.Left containing this scala.Option's value if this scala.Option is nonempty.

    Returns a scala.util.Right containing the given argument right if this is empty, or a scala.util.Left containing this scala.Option's value if this scala.Option is nonempty.

    This is equivalent to:

    option match {
      case Some(x) => Left(x)
      case None    => Right(right)
    }
    right

    the expression to evaluate and return if this is empty

    Definition Classes
    Option
    Annotations
    @inline()
    See also

    toRight

  25. def toList: List[Nothing]

    Returns a singleton list containing the scala.Option's value if it is nonempty, or the empty list if the scala.Option is empty.

    Returns a singleton list containing the scala.Option's value if it is nonempty, or the empty list if the scala.Option is empty.

    This is equivalent to:

    option match {
      case Some(x) => List(x)
      case None    => Nil
    }
    Definition Classes
    Option
  26. final def toRight[X](left: => X): Either[X, Nothing]

    Returns a scala.util.Left containing the given argument left if this scala.Option is empty, or a scala.util.Right containing this scala.Option's value if this is nonempty.

    Returns a scala.util.Left containing the given argument left if this scala.Option is empty, or a scala.util.Right containing this scala.Option's value if this is nonempty.

    This is equivalent to:

    option match {
      case Some(x) => Right(x)
      case None    => Left(left)
    }
    left

    the expression to evaluate and return if this is empty

    Definition Classes
    Option
    Annotations
    @inline()
    See also

    toLeft

  27. final def unzip[A1, A2](implicit asPair: <:<[Nothing, (A1, A2)]): (Option[A1], Option[A2])

    Converts an Option of a pair into an Option of the first element and an Option of the second element.

    Converts an Option of a pair into an Option of the first element and an Option of the second element.

    This is equivalent to:

    option match {
      case Some((x, y)) => (Some(x), Some(y))
      case _            => (None,    None)
    }
    A1

    the type of the first half of the element pair

    A2

    the type of the second half of the element pair

    asPair

    an implicit conversion which asserts that the element type of this Option is a pair.

    returns

    a pair of Options, containing, respectively, the first and second half of the element pair of this Option.

    Definition Classes
    Option
  28. final def unzip3[A1, A2, A3](implicit asTriple: <:<[Nothing, (A1, A2, A3)]): (Option[A1], Option[A2], Option[A3])

    Converts an Option of a triple into three Options, one containing the element from each position of the triple.

    Converts an Option of a triple into three Options, one containing the element from each position of the triple.

    This is equivalent to:

    option match {
      case Some((x, y, z)) => (Some(x), Some(y), Some(z))
      case _               => (None,    None,    None)
    }
    A1

    the type of the first of three elements in the triple

    A2

    the type of the second of three elements in the triple

    A3

    the type of the third of three elements in the triple

    asTriple

    an implicit conversion which asserts that the element type of this Option is a triple.

    returns

    a triple of Options, containing, respectively, the first, second, and third elements from the element triple of this Option.

    Definition Classes
    Option
  29. final def withFilter(p: (Nothing) => Boolean): WithFilter

    Necessary to keep scala.Option from being implicitly converted to scala.collection.Iterable in for comprehensions.

    Necessary to keep scala.Option from being implicitly converted to scala.collection.Iterable in for comprehensions.

    Definition Classes
    Option
    Annotations
    @inline()
  30. final def zip[A1 >: Nothing, B](that: Option[B]): Option[(A1, B)]

    Returns a scala.Some formed from this option and another option by combining the corresponding elements in a pair.

    Returns a scala.Some formed from this option and another option by combining the corresponding elements in a pair. If either of the two options is empty, None is returned.

    This is equivalent to:

    (option1, option2) match {
      case (Some(x), Some(y)) => Some((x, y))
      case _                  => None
    }
    that

    the options which is going to be zipped

    Definition Classes
    Option
    Example:
    1. // Returns Some(("foo", "bar")) because both options are nonempty.
      Some("foo") zip Some("bar")
      
      // Returns None because `that` option is empty.
      Some("foo") zip None
      
      // Returns None because `this` option is empty.
      None zip Some("bar")